[oe] Build suddenly stops and desktop logouts !

[Ranran]

Hello,

I have strange behavior with ubuntu16.04 LTS, in which after building
for couple of hours, suddenly the ubuntu OS logouts.
I see that others also have the same issue but seems that there is no solution:
http://lists.openembedded.org/pipermail/openembedded-core/2016-December/130617.html
and
https://stackoverflow.com/questions/48148169/whenever-running-bitbake-stops-all-application-and-locks-the-system

I have increased my virtualbox memory to 11G, (no swap in my ubuntu)
but it still happens (might be less than before not sure), also
strangely even after increase with "free" command I see that it get
sometimes below ~150M free.

Is there any idea what's wrong?

Thank you,
ran